Extruding apparatus



Oct. 29, 1940.

EXTRUDING APPARATUS Filed Sept. 15, 1958 FIG. 3

INVENTOR A. J N. DUCL 05 A T TOR/V5 Y A. J. N. DUCLOS 2,219,888

Patented Oct. 29, 1940 UNITED STATES PATENT OFFICE to Western ElectricCompany, Incorporated,

, New York, N. Y., a corporation of New York Application September 15,1938, Serial No. 230,029

Claims.

This invention relates to extruding apparatus, and more particularly toa lead press for making extruded lead or lead alloy sheathing onelectric conductor cable.

It has long been a familiar and much used procedure in the art ofmanufacturing electric conductor cables to provide a core comprising oneor more electrically insulated electric conductor strands, with aseamless sheath of lead or lead alloy or the like material, by passingthe cable core longitudinally of itself through a suitable chamber in anextrusion press, so that the press will form the material into aseamless tubular sheath about the core. The operation of such a press isordinarily discontinuous, in that the cylinder of the press is filledwith a supply of the metal to be extruded. This is then ordinarily notentirely extruded but a slug of the metal is left in the bottom. of theextrusion cylinder upon which further molten metal is supplied foranother extrusion. At the end of an operating'period, for example aday's work, it is customary to leave the slug from the last extrusionoperation in the cylinder, where it chills and hardens over night. Thisslug must then in some manner be softened or melted, when operations arere-commenced, to become united with the next charge of metal to bepoured into the cylinder, in order that there may not be any lack ofcontinuity in the metal extruded. When in regular operation the cylinderof such an extrusion press is ordinarily at a relatively hightemperature, although usually not at or above the melting point of themetal being extruded, since the latter is ordinarily semi-solid or solidduring the extrusion. Many devices and methods have been suggested inthe past for melting the left-over slug from a previous operation. Theprime dif ficulty of such procedures has always been the great mass ofthe cylinder itself and its associated parts, which require to be heatedtogether with the slug if an attempt is made to melt or soften thelatter by any direct application of heat.

An object of the present invention isto provide a lead press havingmeans whereby such a slug may be quickly, easily and economicallysoftened or melted for amalgamation with a new charge of metal.

In one embodiment of the invention, a lead press such as is used forsheathing electrical conductor cables may be provided, around the bottomperiphery of its extrusion cylinder, with a multi-turn coil ofelectrical conductor embedded within the walls of the cylinder adjacentthe inner periphery of the cylinder, by means of which a slug of frozenalloy in the cylinder may be softened or melted by heat generated byinduction in the slug by means of a high frequency alternating currentpassed through the core.

Other objects and features of the invention will 6 appear from thefollowing detailed description of one embodiment thereof taken inconnection with the accompanying drawing, in which the same referencenumerals are applied to identical parts in the several figures and inwhich Fig. 1 is a partly diagrammatic view in rear elevation of a leadpress for sheathing electrical conductor cable and constructed inaccordance with the invention;

Fig. 2 is an enlarged broken sectional view on the line 22 of Fig. 1;and

Fig. 3 is a still further enlarged detail of a portion of the showing ofFig. 2.

The embodiment of the invention herein disclosed comprises a lead press,generally of well known construction and mode of operation, which has aframe comprising vertical pillars 2| and 22 and horizontal cross beams23 and 24 supported in any suitable fashion. On the upper cross beam 23is rigidly secured a stationary ram 25. The lower cross beam 24 isrigidly mounted on or secured to a hydraulic cylinder 26 upon the ram 21of which is mounted a die block 28, and upon the die block rests anextrusion cylinder 29. A cable core 30, to be sheathed with lead orother suitable material by the action of the machine, enters the dieblock from the rear through a centrally bored lock nut 3| and passesthrough the die block in the direction of the arrow shown in Fig. '1.The nut 3| serves to secure a tubular core-guide 32 in place within thedie block 28. When the die block and the cylinder are lifted by thehydraulic ram 21 the ram 25 enters the extrusion chamber 33 of thecylinder 29 and forces the alloy contained therein down through thechamber 34 of the die block 28, and forms the alloy as a seamless sheath35 about the cable core 30 as the latter passes through the die proper36 and emerges through the perforated nut 31. In ordinary working theram 25 enters the chamber 33 only so far as the dotted line 38 in Fig.2, which dotted line therefore represents the upper surface of a slug ofalloy 39 which is left behind in the chamber 33 when the cylinder 29 isagain retired downwardly from theram 25 in order that chamber 33 may berefilled with alloy for the next extrusion stroke of the press.

At the end of the days work or other working period, the press willordinarily be left with its parts in the position shown in Fig. 1 andwith a slug 39 of sheath metal or alloy at the bottom of the chamber 33.Ordinarily when work is to be recommenced the slug 39 will have chilledand hardened beyond the point at which its upper surface will amalgamateproperly with a fresh supply ofmolten alloy poured into the chamber 33.Hence in the present invention a ring 90 is positioned within acorresponding recess formed in the wall of the cylinder 29 at the bottomend of the chamber and surrounding that part of the slug 39 which lieswithin the chamber 33. The inner periphery 4! of the ring 40 ispreferably formed to be a smooth continuation of the Wall of the chamber33. The outer periphery of the ring 40 is formed with a peripheralrecess or groove 42 within which is positioned a suitable number ofturns of an electrical conductor to form an induction coil capable ofperforming the function hereinafter described.

It may be noted, incidentally, that presses of the type generallydescribed above are ordinarily intended to be used for sheathing cablecores of a considerable variety of diameters. Hence the core block 28 ismade to be interchangeable for similar blocks whose nuts 3| and 31 andcoreguide 32 are adapted for other diameters of core and thicknesses ofsheath; and, for convenience in making such interchanges and inmanufacturing suitable die blocks, the block 28 is provided with apacking ring 44, so that the diameter of that part of the die blockwhich projects up into the chamber 33 need not be accurately dimensionedas this can be more easily achieved by grinding or otherwise accuratelyforming the outer periphery of the packing ring 44.

At some convenient point in the bottom end of the cylinder 29 a radialrecess 45 may be cut, to

" the terminals 46 and 41 of the coil 43 may be, brought out forconnection to a suitable source communicate with the groove 42, throughwhich 48 of electrical power.

If at any time upon the commencement of the operation of the apparatusthere is a frozen slug 39 present in the extrusion chamber, by passingan alternating electric current of suitable frequency and potentialthrough the coil 43 an alternating electromagnetic field will be set up,principally in the upper part of the slug 39. The eddy currents thussetup within the material of the slug will rapidly and controllably heatthe latter to whatever temperature is necessary to render the materialof the slug able to unite with fresh material poured into the cylinder29. Since the field thus created by the coil 43 exists substantiallyentirely within the material of the slug 39, because of the location ofthe coil substantially at the inner surface of the cylinder wall,practically no energy will be wasted in heating parts of the press, theamount of energy absorbed by the ring 40 being relatively negligible.

Although the invention has been illustrated as embodied in a leadextrusion press of a particular type and for a specific purpose theinvention is by no means so limited, and is limited as to scope andspirit solely by the appended claims.

What is claimed is:

1. In an extrusion press having an extrusion cylinder, means to createan alternating electrical field within the chamber of the cylinder nearthe extrusion end of the cylinder, the said means comprising anelectrical conductor coil embedded within the annular wall of thecylinder at the extrusion end thereof and substantial- 'ly at the innersurface of the wall, there being a end thereof, and an electricalconductor coil housed in the recess and surrounding the extrusion end ofthe chamber, there-being a minimum thickness of chamber 11 between thecoil and the chamber.

3. In an extrusion press, an extrusion cylinder formed wtih a chamberandan annular recess in the innerwall of the chamber at the extrusion endthereof, a guard ring positioned in the recess, and an electricalconductor coil housed in the recess between the guard ring and thecylinder wall and surrounding the extrusion end of the chamber, therebeing a minimum thickness of the guard ring between the coil and thechamber.

4. An extrusion press having an extrusion cylinder and means to createan alternating electrical field within the chamber of the cylinder, thesaid means comprising an electrical conductor coil surrounding the saidchamber and embedded within the walls of the chamber at the extrusionend of the chamber and closely adjacent to the surface of the chamber.

5. An extrusion press having an extrusion cylinder and means to createan alternating electrical field within the chamber of the cylinder, thesaid means comprising an electrical conductor coil surrounding the saidchamber and embedded within the walls of the chamber'at the extrusionend of the chamber and closely adjacent to the surface of the chamber,in combination with a source of. altemating electrical current.

AENEAS J. N. DUCLOS.

